<)! 'I in:
UNIVERSITY OF CALIFORNIA.
. Class No.
ITS INFLUENCE ON
JAMES ATKINSON LONGRIDGE,
MEM. INST. CIVIL ENG. ; HON. MEM. OF NORTH OF ENGLAND INSTITUTE
OP MINING AND MECHANICAL ENGINEERS ;
AUTHOR OF <A TREATISE ON THE APPLICATION OF WIRE TO THE
CONSTRUCTION OF ORDNANCE*; 'INTERNAL BALLISTICS,'
E. & F. N. SPON, 125, STBAND, LONDON.
NEW YORK: 12, CORTLANDT STREET.
UNIVERSITY OF CALIFORNIA.
^Heceived , i8g .
^Accessions No..... Class No..... ..... t
ITS INFLUENCE ON
ITS INFLUENCE ON
JAMES ATKINSON LONGRIDGE,
MEM. INST. CIVIL ENG. ; HON. MEM. OF NORTH OF ENGLAND INSTITUTE
OF MINING AND MECHANICAL ENGINEERS;
AUTHOR OF 'A TREATISE ON THE APPLICATION OF WIRE TO THE
CONSTRUCTION OF ORDNANCE'; 'INTERNAL BALLISTICS,'
E. & F. N. SPON, 125, STRAND, LONDON.
NEW YORK : 12, CORTLANDT STREET,
IN the last chapter of my recent treatise on * Internal
Ballistics' I alluded to the new powders which were then
attracting the attention of artillerists.
Keferring to their probable nature, I observed that the
introduction of any ingredients which would either increase
the volume of gas or its temperature, or both together,
would not only explain the apparently anomalous action of
these new powders, but probably result in the discovery of a
still more powerful agent.
Since then this has apparently been accomplished, and the
old charcoal powder appears to be doomed to yield to this
more powerful rival.
But the adoption of this rival, whose properties are as yet
only imperfectly known, is not to be viewed without anxiety.
Can it be used with advantage, and above all with safety, in
our new type forged steel guns ? If not, what changes will
its use involve in gun construction ? What will be its effect
as regards erosion ? How will it be affected by storage and
change of climate ?
These are important questions, to which I do not pretend to
give complete answers, but I hope that the following remarks
will be of some use in directing attention to the problems
upon the solution of which future gun construction and
ballistic practice largely depend.
J. A. LONGKIDGE.
GEEVE D'AZETTE, JERSEY.
I. INTRODUCTORY -. . . . . 1
II. NATURE OF THE POWDER PRODUCTS OF COMBUS-
TION POTENTIAL FORCE COMPARISON WITH
OLD POWDERS . . . . , 4
III. BALLISTIC EFFECT OF NEW POWDERS IN FRENCH
AND GERMAN GUNS COMPARISON OF B.N. AND
NOBEL'S POWDER 9
IV. PRESSURES IN THE CHASE WITH NEW POWDER
COMPARISON WITH PRESSURES FROM PEBBLE
V. EFFECT OF THE NEW POWDER ON EXISTING GUNS . . 24
VI. INFLUENCE OF THE NEW POWDER ON THE DESIGN
OF GUNS 35
VII. CONCLUSION 39
1. In few paths of science has the march of progress in
the latter part of the nineteenth century been more remark-
able than in the development of material for warfare.
2. Less than half a century ago, the heaviest guns in our
service were the old 68-pounders, weighing about five tons,
and firing, with a charge of 20 Ibs. of powder, a spherical
68 Ib. projectile to which it gave a velocity of about 1500 feet
per second a ballistic effect equal to an energy of 1060 foot-
3. The heaviest service gun of the present day is the
110-ton gun, firing a projectile of 1800 Ibs., with a charge of
850 Ibs. of powder, and a velocity of 2100 feet per second,
equivalent to an energy of 55,000 foot-tons.
4. In the absence, in this country, of the definite know-
ledge of the action and properties of powder (acquired through
the researches of M. Sarrau. in France), the adaptation of
the powder to the gun, and, vice versa, of the gun to the
powder, has been a problem, the solution of which, so far
as it has been solved, is of an empirical nature, so that the
progress made in gun construction and powder manufacture
has been of a somewhat erratic description.
5. After the day of pebble powder came that of P 2 or
C and C 2 , then that of prismatic, succeeded by that of
brown cocoa, and finally that of the so-called E.X.E., which
2 SMOKELESS POWDER.
a few months ago was looked upon as the ne plus ultra of
gunpowder for heavy guns.
6. The line taken by gunmakers has been tolerably con-
sistent throughout. They have aimed at reducing the strength
of the powder, keeping down the pressure, and making up for
this by increased charges, enlarged powder chambers, and
increased length of gun.
Following out this line they have arrived at charges of
one-half, or more, of the weight of the projectile, and at guns
of 30 to 40 calibres in length, but with a maximum pressure
limited to about 17 tons per square inch.
7. In vain the argument has been urged that, by strengthen-
ing the guns instead of weakening the powder, the same
ballistic results could be obtained with greater convenience
and less expense. It has been shown, both theoretically and
practically, that wire guns can be made as safe under a
pressure of 30 tons as forged steel guns under a pressure of
17 tons ; but though a few experiments in this direction have
been made at Woolwich, they have been made in a half-
hearted way, extending over long intervals of time, daring
which the construction of the type of* forged steel gun has
been rapidly proceeded with, and may be said practically to
include the whole of our new armament.
8. These latter guns are designed specially for the use of
such powders as the brown cocoa and E.X.E., that is to
say, powder of which a very large charge is required.
9. Until quite recently our artillerists have been in a
happy frame of mind. They had got, or were very rapidly
getting a sufficient supply of large guns of what they thought
to be the best possible type, and they had the new E.X.E.
powder, the best powder in the world. They had but to rest
and be thankful.
10. That rest has been of short duration. From Germany
and France came rumours of a new powder giving wonder-
ful ballistic results, and at the same time smokeless, or
11. Although much secrecy has been maintained with
SMOKELESS POWDER. 3
respect to the nature of the new powders, yet the results have
been so far made public, that it is no longer doubtful that
they will give ballistic results largely exceeding those obtained
from cocoa and E.X.E., with considerably reduced charges
and no excessive maximum pressure.
12. This being so, the question arises, how far are our
new type guns suited to the new powder, and to what extent
shall we require a new armament, in order to reap the full
advantage of the new powder ? It is proposed to discuss
these questions by the light of such knowledge as the author
can bring to bear upon the subject.
13. This knowledge is too limited to enable him to produce
a "treatise on the use of smokeless powder," but it may
perhaps be useful in explaining in some degree the difference
of action between the old and new powders, and the approxi-
mate results obtained by the use of the latter, both as
regards ballistic effect and the development of construction
of guns suitable to its use.
14. The subject is divided into the following parts :
The nature of the new powder and the results of its de-
composition as regards the volume of gas produced per unit
of weight, the heat evolved, the temperature of combustion
and a comparison with pebble powder, as a type of the old
powders, the " Potential " and " Force " of the powder.
An examination of the ballistic effects of the new powder
in French and German guns.
An inquiry into the pressures in the chase of Canet's
15 cm. Q.F. gun, with B.N. powder, and a comparison with a
full charge of pebble powder in the same gun.
An examination into the effect of using the new ^powder
in the existing new type forged steel gun.
A few remarks on the influence of the new powder on the
design of guns, and finally some general conclusions.
NATURE OF THE POWDER PRODUCTS OF COMBUSTION
POTENTIAL FORCE COMPARISON WITH OLD POWDERS.
15. The very remarkable results which have been recently
obtained from smokeless powder in France and Germany,
point to an entire revolution in artillery practice, as well as
to a complete revision of the system of gun construction and
the formulae of internal ballistics.
16. M. Sarrau's formulae of velocity and pressure, which
are very approximately correct for charcoal powders, such as
the ordinary black and brown powders, are no longer appli-
cable to the case of the new powders which give much higher
velocities with smaller charges and reduced pressures. This
must consequently lead to modifications in the proportions
of guns, if it be admitted that these proportions are de-
pendent on the pressures existing in different portions of the
17. The superior results obtained from the new powders
are mainly due to the fact that, with them, nearly the whole
of the powder is converted into permanent gases, whereas
with the old powders only about 43 per cent, is so converted,
the remaining 57 per cent, being inert matter existing in the
gun in the form of a very finely diffused liquid, which, when
cooled down, solidifies ; and is not only mainly the cause
of the smoke, but also in all probability one cause of the
18. Although the chemical constitutions of the new
powders are kept as secret as possible, they are probably all
closely allied to that of Nobel's smokeless powder, that is to
say, the main ingredients are nitre-cellulose and nitro-
glycerine, to which is added nitrate or perchloride of
ammonia and a little camphor.
U IT 171
19. An analysis of the reactions which take place on the
explosion of this mixture is given in the Appendix A, and
from this it appears that the whole of the products consist of
permanent gases and watery vapour, the volume of which
amounts to about 705 cubic centimetres for each gramme of
20. Further, that the heat evolved, after allowing for the
vaporisation of the water, is about 1 7143 French units per
gramme of powder.
21. The mean specific heat of the products is found to be
about -1989, and their theoretic temperature about 8673 C.
22. Appendix B contains a similar examination of the
results of combustion of pebble powder, which may be taken
as a type of the old powders, from which it appears that the
following are the results :
Volume of gas from 1 gr. of powder .. 286 cm. cube.
Gramme units of heat 690*2
Mean specific heat -187
Theoretic temperature of products .. 4:750 C.
23. The temperatures above calculated may be called the
" Theoretic or Potential Temperature." The actual tempera-
tures are probably not more than one-half, owing partly to
the cooling effect of the walls, and partly to the increase of
the specific heat at the high temperature and pressure exist-
ing in a gun ; but they probably represent the relative effect
of the two powders as regards the temperature of the pro-
ducts of combustion.
24. The following comparison of the two powders may
therefore be made :
Volume of gas at C. and '76 metres from
1 gramme ofi
Gramme units of heat evolved from 1 gramme
Mean specific heat of products
Theoretic temperature of products
6 SMOKELESS POWDER.
Potential of NobeTs Powder.
25. By the " Potential " is meant the mechanical equiva-
lent of the heat developed by the combustion of unit of
weight of the powder, or E Q ; when Q is the quantity of
heat evolved, E = 436 in French unities, or 772 in English
unities. Now it has been shown that Q = 1*714 units per
gramme, or 1714 per kilogramme.
436 x 1714
Therefore, Potential = iQOO = ^^ ' ^ me tre-tons
per kilogramme, or 1095 foot-tons per Ib. of powder.
26. In the treatise on ' Internal Ballistics ' * (page 8),
there is a table of the " Potentials " of various explosives,
and that of pebble powder is given as 460 foot-tons per Ib.,
or considerably less than the half of that of Nobel's powder ;
but, as was there observed, the " Potential " of an explosive
must not be confounded with the mechanical effect which
may be obtained from it, nor with the pressure developed by
its combustion in a closed vessel.
27. At page 50, ' Internal Ballistics/ the symbol "/" was
used to denote what is called by M. Sarrau, the " force " of
the powder, and it was defined by the relation
Po Vp TQ
7 " 273 '
where p Q is the atmospheric pressure = 103 33 kilog. per
square decimetre ;
V Q is the volume of gases from unit of weight at tem-
perature zero and atmospheric pressure ;
T is the absolute temperature of combustion.
Taking the kilogramme as unit of weight, the volume of
gas is, for Nobel's powder, 705 x 1000 cm. 3 or 705 dm. 3
If the actual temperature of combustion be taken as
one-half of the theoretic value, or 4326 C., the absolute
= 4326 + 273 = 4599.
* ' Internal Ballistics,' by J. A. Longridge. Spon, London, 1889.
Therefore / =
103-33 x 705 x4599
= 1,227,022 kilogrammes per square decimetre.
The value of / for pebble powder is given at page 51,
' Internal Ballistics,' as 263,600, consequently the ratio of/,
as between Nobel's powder and pebble, is = 4 655.
28. The " force," /, as denned by M. Sarrau, is the abso-
lute pressure of powder exploded in a close vessel entirely
filled ; that is to say of gravimetric density = 1, and with
ordinary powder p = f - - , where a is the proportion of
non-gaseous matter, which, with ordinary powders, is about
57 of the weight. In Nobel's powder a = 0, consequently
p =/A and if A = 1, p =/= 1,227,022 = 122 '7 kilog, per
mm. 2 = 78 '52 tons per square inch, which is nearly double
that of pebble powder.
29. It is therefore apparent that the Nobel powder is
capable of producing much higher pressure than the pebble,
and yet in practice it gives higher velocity with less
charges and lower pressures.
This apparent paradox is easily seen to be due to the
absence of inert matter, the whole of the powder being con-
verted into gas, instead of only 43 per cent, as in pebble
powder, and the total volume of gas being 705 cm. 3 per
gramme of powder, against 286 cm. 3 for pebble, whilst at
the same time the temperature of combustion is about
30. Actual Pressure in gun. The actual pressures in guns
are of course much below the calculated values of p, for two
reasons : first, because there is a loss of temperature due to
the cooling action of the chamber walls, and secondly,
because by the time the whole of the charge is burnt, the
projectile has moved a considerable way along the chase
and so increased the space to be filled by the evolved
If, for instance, there be a maximum pressure of 15 tons in
8 SMOKELESS POWDER.
the gun (assuming for the moment that there is no loss of
heat), we have
p = 78-52, and p = 15,
v = v x 3 506 ;
so that, if the rate of burning of the powder were suitable, a
full charge of gravimetric density = 1 might be fired, and
yet the maximum pressure not exceed 15 tons per square
inch, which would be attained when the projectile had moved
3 ' 506 times the length of the charge along the chase.
31. Another advantage will probably be the absence of
fouling, as the whole of the matter is converted into gases,
which leave little or no residuum in the gun.
32. Erosion. As regards erosion, experience must decide.
But it may be said that on the one hand, the products of
combustion being entirely gaseous, instead of a mixture of
gas and fluids, will probable erode less ; whilst on the other
hand that the increased temperature and volume will tend
to augment that erosion.
With the new powder, the temperature no doubt falls
more rapidly than with the ordinary powder, because the
loss of heat being a function of the difference of temperature
between the gases and the gun, is greater with high tempera-
tures ; whilst on the other hand, with ordinary powder, it is
quite possible that whilst the guns are expanding, heat is
communicated to them from the highly heated liquid, arising
from the non-gaseous portion of the charge diffused through
them. The question of erosion must therefore be determined
by experience. So far as our present knowledge goes, the
smokeless powder in this respect appears to possess the
BALLISTIC EFFECT OF NEW POWDERS IN FRENCH AND
GERMAN GUNS COMPARISON OF B.N. AND NOBEL*S
33. Formulas for Pressure and Velocity. It is not surprising
that the formulae which represent the ballistic action of the
old powders are found to be inapplicable to the new powders,
and although it is probable that M. Sarrau has already so
modified his formula as to make it represent the action of
the new powder, it is scarcely likely that the results of his
investigations will be made public at present.
34. Although the experimental data published are very
limited, it will not be without interest to examine them care-
fully. These data are contained in notices of results of
firing, obtained at Essen in July and August 1889, with
Nobel's powder fired from four different guns, and of the
results obtained from the French B.N. powder fired from
10 cm. and 15 cm. guns, or 3*937 and 5*90 inches calibre
35. An examination of these results leads to a rather
remarkable conclusion, which, however, must be taken with
It is as follows :
1st. The muzzle velocity of the projectile is proportional to
the f th power of the weight of charge.
2nd. The maximum pressure in the gun is proportional to
the square of the weight of the charge.
P = B w 2 . (2)
The coefficients A and B are not constants, but are composed
10 SMOKELESS POWDER.
of various factors, which are functions of the form, dimension,
and rate of burning of the grain in fact, what are called by
M. Sarrau the " characteristics of the powder of the weight
of the projectile, the calibre of the gun, and the length of
travel of the projectile.
In M. Sarrau's formula, he introduces another factor A,
the gravimetric density, but this is in itself a function of the
weight of charge, and of the calibre of the gun.
Taking, for instance, M. Sarrau's monomial formula for
velocity, as given at page 98, * Internal Ballistics/
where H is a factor containing the " force " and " charac-
teristics " of the powder ;
w = weight of charge ;
A = gravimetric density ;
I = length of travel of projectile ;
W = weight of projectile ;
c calibre of gun.
Now, if X = equivalent length of chamber,
weight of charge
capacity of chamber 7854: c 2 A.
substituting which in the above we get
and it is the part within the bracket that is represented by
A in (1).
In like manner Sarrau's formula for pressure is
= K o" - 2 >
for A becomes
and the part within the bracket represents the B in (2).
36. From this it appears that in passing from the old to
the new powders, the index of w is increased from f- to f in
the expressions for velocity ; and from 1 75 to 2 in that for
pressure, an increase which might be anticipated from the
absence of inert matter in the products of combustion of the
The coefficients A and B of course are different with dif-
ferent guns, and different brands of powder.
87. The results of the experiments made at Essen in 1889
have been published in the ' Kevue d'Artillerie,' vol. xxxv.
These experiments were made with Nobel's powder fired from
four different guns, the details of which are given in the
following Table, No. I.
Number of Gun.
Calibre in inches
Length of gun in calibres
\Veight of gun Ibs
of projectile .. ..
From the results obtained at Essen the following Tables
II. and III. have been constructed.
Table II. gives the value of the coefficients A and B of
formula (1) and (2) ( 35).
Table III. gives the velocities and pressures, calculated
with these coefficients employed in formulae (1) and (2), and
compared with the results actually obtained at Essen.
66 to '80
66 to -792
1 to 1 20
1 to 1-10
66 to 1-17
2-2 to 3-74
3-3 to 3-54
Eound . .
VELOCITY Feet per
JL V .
PRESSURES Tons per Square Inch.
38. The experiments made with the French smokeless
powder B.N. were made with two of Canet's quick firing
guns of (10 cm.) 3 '937 inch and (15 cm.) 5 '905 inch calibre,
each of 48 calibres in length.
This is the total length of gun over all, the length of
travel of the projectile being about 38 calibres.
The powders used were all of the description called B.N.
In the 3-937 inch gun, three different lots were used, which
may account for the difference of the coefficients A and B,
whilst in the 5 905 inch gun the powder was of the same
39. Table IV. gives the values of A -and B, and Table V.
the comparison of the observed with the calculated ballistic
results, corresponding with Tables II. and III. for the Nobel
5-28 to 8-58
7-93 to 8-16
7-93 to 9-92
17-64 to 33-08
Round . .
VELOCITY feet per second.
PRESSURES tons per square inch.
14 SMOKELESS POWDER.
40. From these tables it appears that the formulae (1) and
(2), above given, represent very closely the results obtained
by experiments, and it is therefore probable that the indices
75 and 2 denote the relations between the weight of the
charge and the velocity and pressure respectively, at any rate
it is so in these guns.
41. A comparison may be made between the French B.N.
and the Nobel powder, first as regards the energy of the
projectile per Ib. of powder, and second as regards the energy
per ton weight of gun.
For this purpose take the (10 cm.) 3 '937 inch Canet gun,
weighing 4620 Ibs., and compare it with the 3*287 inch
Krupp gun, weighing 2310 Ibs. ; the Canet gun being fired
with B.N., and the Krupp gun with Nobel's powder of 1557
inch size of grain.
It is assumed that the strain on the two guns is the same,
that is to say, that the charge shall be such as will give the
same maximum pressure in the two guns, and that this
pressure shall be 18 '17 tons per square inch, as in the fourth
round of this gun in Table V., giving a velocity of 2615 foot-
Therefore, in the Canet gun,
Energy per ton of gun 657*1 foot-tons,
per Ib. of powder 136*7 foot-tons.
42. In the 3*257 inch Krupp gun, in order to give the
pressure of 18* 17 tons, the weight of charge of the * 1557 inch
grain Nobel powder is found by the equation P = 1 215 w 2 ,
and the velocity with this charge would be
V = 920 w" 75 = 2537 feet per second;
Energy per ton of gun = 771 7 foot-tons.
per Ib. of powder = 205 8
43. If the powder of 0*1969 inch grain were used, the
requisite weight of charge would be 4*531 Ibs., and the
velocity 2730 feet per second, giving the Energy of the
15 Ib. projectile = 774*7 foot-tons, which gives
Energy per ton of gun = 751*2 foot- tons.
per Ib. of powder = 171
44. These results are brought together for comparison in
the following Table.
3-937 inch Gun.
3-287 inch Gun.
3 -287 inch Gun.
Energy per ton of gun
Energy per Ib. of powder . .
45. The results show somewhat in favour of the Nobel
powder, both per ton of gun and per pound of powder.
46. It must further be observed that the 3 937 inch gun
has the advantage over the 3 287 inch gun, in being a gun of
48 calibres as against 40 calibres in the latter. If the guns
had been what is termed " similar guns " and similarly
loaded, the velocities would have been the same, but the
weight of projectiles as the cubes of the calibres, con-
sequently the energy of similar guns increases as the cube of
the calibre, which in the present case is in the ratio
16 SMOKELESS POWDER.
Consequently, had the guns been similar and similarly
loaded, the total energy would have been
as 1355 : 788-5;
so that not only is the energy of the smaller gun greater than
the due proportion, but this is the case under the disadvantage
of being the shorter gun.
47. So far then as these experiments go, it appears that
the Nobel powder is superior in ballistic power to the B.N.
SMOKELESS POWDER. 17
PRESSURES IN THE CHASE WITH NEW POWDER COMPARISON
WITH PRESSURES PROM PEBBLE POWDER.
48. In the absence of further experimental' data it is
impossible to deduce the relations between the velocity and
pressure and the other ballistic elements, such as the length
of travel of projectile, weight of projectile, and calibre of the
gun, so that the coefficients A and B given above can only
be made use of for " similar " guns.
49. It is very important to ascertain as far as may be
possible, the distribution of pressures along the chase whilst
the projectile is travelling to the muzzle.
50. As has already been shown, there is reason to believe
that in a close vessel impermeable to heat, the pressure from
the new powder would be about double of that given by the
old black powder. Consequently, as in practice the maximum
pressure is not greater, it follows that the rate of combustion
must be slower, thus giving more time for the projectile to
get out of the way, and by thus increasing the space, keep
down the pressure.
It is also quite possible that the combustion may go on for
a considerable time after the maximum pressure is attained,
and that thus the pressures towards the muzzle may be
greater than with the ordinary powders.
51. As this is a point of great importance relative to
the designing of guns, the question requires examination,
so far as the limited experience available enables it to be
52. Consider the case of the (15 cm.) 5*905 inch Canet
18 SMOKELESS POWDER.
Q.F. 15 cm. gun of 48 calibres with B.N. powder, of which
the following are the ballistic elements :
CANET'S Q.F. 15 CM. GUN.
Calibre of gun ........ 5*905 inches.
Length of travel of projectile .. 224*5
Equivalent length of chamber .. 53
Capacity of chamber ...... 1500 cubic inches.
of chase ........ 6174
Total capacity of gun ...... 7674
Number cf expansions Z- = 5*116
Weight of charge ........ 33*08 Ibs.
Weight of projectile .. .. .. 89
Weight of gun ........ 6*29 tons.
Muzzle velocity ........ 2750 f.s.
Total energy = 4665 foot-tons.
Energy per ton of gun ...... 744' 6
per Ib. powder ...... 141*0 ,
Maximum pressure ...... 18*81 tons per sq. in.
53. First, it may be asked, what must have been the mean
pressure in the gun ? The total energy expended on the
projectile was 4665 foot-tons, to which must be added that
expended in overcoming friction and expelling the gases, &c.
This may be estimated at an additional 20 per cent, making
the total energy 5598 foot-tons.
Now the area of section of the projectile is 27*4 inches, and
the travel 18*4 feet. Therefore, if p be the mean pressure,
p = -- -- - = 10*92 tons per square inch.
54. Next, if it be granted that the pressure in a close
vessel would be 78 * 53 tons per square inch, and that the pro-
ducts of combustion act as a perfect gas, it may be inquired,
at what point in the travel of the projectile will the pressure
be reduced to the maximum pressure of 18 * 81 tons ? This
can only be approximately ascertained in the absence of
SMOKELESS POWDEE. 19
knowledge as to the loss of heat due to cooling, but from the
considerations set forth in ' Internal Ballistics/ Chapter V.,
it would appear that this is not very great. Leaving this
loss out of account, there is the relation ^ = ( ) , where
PO and V Q are the original and p and v the final pressures and
volumes, and as the volumes are proportional to the lengths,
the relation becomes = (= ) . Now let 1 Q be the length
of the bore which would be occupied by the charge at
gravimetric density = 1, and I the distance from the breech
at which the pressure is reduced to p = 18 '81, then
55. For ordinary powder the space occupied at gravimetric
density = 1, is 27 7 cubic inches per Ib. or 1 decimetre cube
per kilogramme, and when the charge is thus spaced it is said
to be of gravimetric density equal unity. If, however, the
space be any other number, say 30 inches to the Ib., the
gravimetric density is said to be
56. It is as well to observe, however, that, with the French,
" densite gravimetrique " has a different meaning.
" Densite gravimetrique "is the weight of 1 cubic deci-
metre of powder, not pressed together except by its own weight.
Consequently it is evident that the " densite gravimetrique " of
a given powder is dependent partly on its absolute density,
i. e. specific gravity, and partly on the size of the grain. For
instance, the French powder F x has an absolute density of
1 * 750, whilst its gravimetric density is 830 to 870, whilst
the WJij-, which has nearly the same absolute density, has a
gravimetric density of 1 03 to 1 17.
The equivalent of " gravimetric density " in French is not
" densite gravimetrique," but '* densite de chargement."
20 SMOKELESS POWDER.
57. As is well known, with the ordinary old powders 27 7
cubic inches is the space occupied by 1 Ib. of powder. But
this is not so with the new powder. With respect to this there
is much reticence. It is, however, probable that 1 Ib. of this
powder may occupy about 31 cubic inches of space, and it is
on this assumption that the following remarks are made.
Though the conclusions arrived at may not be quite
correct, yet they will be relatively so, and will therefore be
useful in the examination of the ballistic properties of the
58. Assuming, then, that the space occupied by 1 Ib. of
powder is 31 inches, the length of bore 1 Q occupied by the
charge is easily determined.
The charge being 33*08 Ibs., and the area of the bore
27 4 inches, we get
_ 33-08 x 31 Q _ .
Length = = 37-42 inches.
59. Let, then, A D (Fig. 1) represent the bore of the gun*
A B the " equivalent length " of the chamber, that is to say,
a length of bore whose capacity is the same as that of the
chamber, and B D the travel of the projectile, and let A A be
the length of the bore which would be occupied by the
charge at gravimetric density = 1, that is to say, in the
present case 37 42 inches. Then, if the powder were fired in
a close vessel, the pressure would be 78 53 tons per square
inch ; but as the projectile moves away the space increases,
and the contest between the evolution of gas and the increas-
ing space goes on until a maximum pressure is reached. If
it be assumed that all the powder is burnt at this time, the
point Ci, on the curve F C x D, corresponding to this maximum
pressure, will denote the position of the projectile, and the
ordinates between C and D the respective pressures on the
bore as the projectile moves to the muzzle ; the curve
F G! D being calculated from the formula
The ordinates between B and C* are indeterminate, and
depend upon the rate of evolution of the gas, the weight of
projectile and other elements, but it may be assumed that
approximately the pressure curve is represented by the curve
B G! D! D, and that the point of maximum pressure is at C 1?
1 18 -53 torus
and that the total work done on the projectile is represented
by the area of the curve multiplied by the area of the bore
of the gun.
60. Taking the unit for abscissa in feet, and for the ordinate
in tons per square inch, the area of the curves A GI D t D is
found to be 210*2, which is the foot-tons per square inch of
* The assumption that the curve from B to C t is one-fourth of an ellipse
has been found by the author to give very satisfactory results.
bore; and multiplying this by 27*4 the area of the bore
gives 5761 foot-tons. If from this be deducted 20 per cent,
for the resistance, friction, and expulsion of the gases, there
remains 4629 foot-tons for the energy of the projectile.
This was found by experiment to be 4665 foot-tons.
It may therefore be concluded that the pressure curve
(Fig. 1) represents, approximately, the pressure in the gun
with a 33 Ib. charge of the new powder.
61. Let now this be compared with the corresponding
diagram of the same gun fired with a full charge of pebble
The capacity of the chamber being 1500 cubic inches, the
full charge will be
Appendix C, gives
Muzzle velocity ..
Pressure on projectile
= 54 Ibs., which, as is shown in
2570 feet per sec.
22 -00 tons.
Therefore the energy is
2570 2 x 89
= 4073 foot-tons,
Energy per ton of gun
per Ib. of powder . .
650 -2 foot-tons.
62. The following Table shows the comparison between
the B.N. and pebble powders in the 5 * 90 inch gun.
Per Ton of
Per Lb. of
63. If a pressure curve be constructed for the pebble
powder in the same manner as above described, and super-
imposed upon the curve for the charge of 33 08 Ibs. of B.N.
as in Fig. 2, the difference in the distribution of pressure is
very strikingly seen.
64. The maximum pressure on the base of the projectile
is 18 * 81 tons per square inch with the B.N., and 22 tons with
the pebble powder, but the position at which it attains its
maximum is when the shot has travelled 59 inches in the
first case, against 16 inches in the second.
Again, the final pressure is 5 65 tons per square inch with
the B.N., against 3 1 tons with the pebble powder.
24 SMOKELESS POWDER.
EFFECT OF THE NEW POWDER ON EXISTING GUNS.
65. Enough has now been said to show that the new
powder is a revolutionary element in ballistic practice, and
that it must consequently exert a corresponding influence
on gun construction.
66. It is therefore very important to examine what will be
the effect of using such powder in the present new type steel
guns, which were designed for the older powders, such as the
black and brown prismatic, and the still later E.X.E. powder.
67. These powders are characteristically weak powders,
that is to say, they burn slowly and give low pressures in
guns. The effect is made up by largely increasing the
charges, and in order to give time for the entire combustion
and also for utilising the expansive force of the gases, the
guns are made very long.
In order to contain the large charges and also to reduce
the length of the gun, enlarged powder chambers are
adopted, with, however, the disadvantage of increasing the
size of the breech mechanism, and the strain upon it.
68. Now, in the first place, it may be asked what will be
the effect of using the new powders on these guns ? It is
claimed for the new powders that, in addition to their quality
of smokelessness, they will give vastly higher ballistic
results, while they will strain the gun less owing to their
low maximum pressure, and this statement has been used
as an argument against the necessity of adopting wire
guns, instead of the usual forged steel construction.
68a. It is not intended to enter here into the questions of
the relative cost of production, the greater freedom from
SMOKELESS POWDER. 25
latent defects, the quicker production, or the relative facilities
of repairs, in all which respects the wire system has
undoubted advantages. But it is desired to show that, if
the full advantage is to be obtained from the high ballistic
properties of the new powder, it can only be obtained by the
use of comparatively high pressure, and consequently, very
strong guns, such as can only be produced by the wire system
69. It is argued that the advantages of the new powders
may be utilised in two ways.
70. Either by retaining the present initial velocity with
the benefit of a great reduction of pressure, or on the other
hand by retaining the present maximum pressure of about
16 tons per square inch, and thus obtaining a very great
increase of velocity, although admittedly retaining the
disadvantage of a great length of gun.
71. The former alternative is thought to be the better
for field guns, as they cannot be lengthened without increase
of weight, which is inadmissible. Morever, the weight of
cartridges could thus be reduced, consequently more of them
could be carried ; whilst it has also been said that, as the
pressures are reduced, the strain on the gun carriage would
72. This last assertion is, however, a mistake. The effect of
the strain on the carriage is proportional to the work done
on it, and this varies as the square of the velocity of recoil,
which velocity, cseteris paribus, is in proportion to the
velocity of the projectile, and has nothing to do with the
pressure by which that velocity is created.
Consequently, if the muzzle velocity be unchanged the
strain on the carriage must be the same, and if, by the use
of the new powder, the velocity be increased, the strain on the
carriage must be increased correspondingly.
73. This is of course slightly modified by the fact that, in
calculating the velocity of recoil, a portion of the weight of
the charge must be taken into account, as well as the weight
of the projectile, but the effect of this will be comparatively
26 SMOKELESS POWDER.
small, and in the case of increased velocity of the projectile,
will be far less than the increase due to the increased
velocity of the projectile, which is not a function of the
maximum pressure, but depends on the mean pressure, which
is quite another thing.
74. As regards the length of gun required for the new
powder, it is argued that by increasing the pressure it would
be necessary also to increase the length of the gun to a
practically impossible extent.
75. But this also is erroneous, for it apparently rests on
the assumption that the maximum pressure can only be
increased by increasing the weight of charge, and that unless
the length of the chase be correspondingly increased, part
of the charge will be blown out of the muzzle unburnt.
76. Now the maximum pressure depends, not altogether,
nor indeed principally, on the weight of the charge, but is
chiefly affected by the rate of evolution of the gas, which
is regulated almost ad libitum by modifying the form and
size of the grain.
It is therefore quite practicable to increase the maxi-
mum pressure, even if the weight of charge be diminished.
77. This will be the more evident after the following
examination of the action of the powder in a gun.
78. In the first place, reverting to Fig. 2 which shows
the pressure in the same gun when fired with charges of
33*08 B.N. and 54 Ibs. P respectively; in order to complete
the curves the pressures behind the points of the maximum
must be indicated.
79. According to M. Sarrau's formulae for ordinary powder,
if P be the pressure on the breech, P the maximum
pressure on the base of the projectile, making use of Eng-
lish unities of pounds for weight and tons per square inch
w and W being the respective weights of charge and projectile.
SMOKELESS POWDEE. 27
Another formula which is said to give better results,
especially with slow powders, is
80. Making use of this latter formula and the weights
corresponding to Fig. 2, we find
For B.N. powder P = P 1^ = 1 19 P.
For pebble P = P = 1-30 P.
From which the breech pressures corresponding to the
maxima in the diagrams are 22 -38 and 28 -6 tons respec-
Setting off these ordinates at the breech the line C^
represents the internal pressure in the gun when the pro-
jectile is at Cj, and a line parallel to it, such as g g^ represents
the pressure when the projectile is at any other part g.
81. What is most important to note is that whilst the
maximum pressure is considerably less with the B.N. powder,
although the work done is nearly 15 per cent, more, and
the powder charges 40 per cent, less, the pressures are
thrown so much further forward, that the B.N. powder if
fully utilised will require a very differently proportioned
gun, one, namely, in which there is about the same strength
behind the point of maximum pressure, but very much
greater strength in front of it.
82. Taking for instance the point g lt Fig. 2, at 110 inches
from the muzzle, the pressure to be resisted will be 10 tons
per square inch with the B.K powder, as against 5 J tons with
83. It is quite true that this pressure may be reduced by
reducing the charge of the B.N. powder.
84. If, instead of firing with 33 * 08 Ibs., the charge was
reduced to 28 f 52 Ibs., the velocity would be the same as
that given by the 54 Ibs. of pebble powder, and the maximum
pressure would be reduced to 14 tons per square inch. The
length of charge would be 30 inches of the bore.
85. The dotted curve, Fig. 3, is constructed from these
data, and being superimposed on the diagram for 54 Ibs. of
pebble powder, shows the respective action of the two
28 54 B.N
224-- 5 -
powders in the same gun, while producing the same ballistic
86. It is evident that a gun designed to sustain the
pressures of the pebble powder is insufficient in strength to
sustain the pressures of the new powder in all that part of
the chase commencing at about 180 inches from the
87. To elucidate this, let an examination be made of the
Eoyal Gun Factory 6 a B.L. gun, MAKK IV. of the follow-
ing ballistic elements :
Length of rifling ..
Capacity of chamber
Equivalent length of ditto
Total capacity of gun ..
Weight of projectile
1364 cube inches.
5105 cube inches.
1980 feet per second.
16 % 50 tons per sq. in.
88. In order to compare this gun with the 15 cm. Canet
gun, it must first be considered on the supposition that it is
lengthened so as to make the travel of the shot the same,
viz. 224*5 inches, and then determined what would be the
muzzle velocity with the same charge of 48 Ibs. of E.X.E.
powder but with a projectile of 89 Ibs.
89. From such data as are at the author's disposal it
appears that the " characteristics " of the E.X.E. powder
Log a = -06136
Log/3 = - 1-47844
Making use of which in Sarrau's binomial formulae for
V = 2444 feet per second.
90. This is the velocity which is taken as a basis of com-
parison with the Canet gun fired with B.N. powder.
Now, by formula (1)
V = 198 to*,
and making V = 2441 gives
w = 28 -52 Ibs.
Then by formula (2)
P = -0172w; 2 ,
which making w = 28 52 gives
P = 14 tons per sq. inch
for the Canet gun.
The comparison is therefore as follows :
Canet 15 cm. gun ..
28 -52 B.N.
R.G.F. 6 in. Mark IV.)
Thus, with 2J tons less pressure the Canet gun only
requires about T 7 ^ of the charge required of E.X.E.
91. It remains, however, to be seen how the variations of
pressure throughout the chase take place in the two guns,
and for this purpose recourse must be had to pressure curves,
obtained as above described. These, though not accurately
correct, represent approximately the real pressures. The
curve for the E.X.E. powder is obtained by making use of
the formula given in 'Internal Ballistics,' page 172, with
allowance of 20 per cent, for resistance, and is represented by
the full line in Fig. 4.
92. The curve for the B.N. powder is obtained as follows :
The charge of 28-5 Ibs. at gravimetric density = 1 would
occupy 28-5 x 31 = 883 cubic inches, which is equal to
30 inches of- the bore, and the initial pressure in this space
would be 78-52 tons per square inch. Therefore the equa-
tion to the curve is
from which the curve represented by the dotted line, Fig. 4,
Placing the two curves over each other, as shown in the
SMOKELESS POWDEE. 31
figure, it is seen that, although the maximum pressure of the
B.N. powder is 3 tons less than that of the E.X.E., yet it is
thrown about 39 inches further forward, and that at this
point the pressure is about 4 tons per square inch greater
than it is with the E.X.E. at the same point in the gun.
93. To pass from this to the Mark IV. gun of the actual
length, it is sufficient to cut off from the diagram the excess
of length in front of A ; the length up to A being that of
the travel of the shot with Mark IV. gun, viz. 127 inches.
Then, by subtracting the areas A A! G! C and A A 2 C 2 C from
the original areas of the two curves, the remaining areas
represent the work done in the two guns if reduced to the
length of the actual Mark IV. gun.
The original areas are 4537 for each, and the deductions
1299 and 1032; therefore the remaining areas are 3238 and
3505 respectively, representing the energies of the two guns
corresponding to muzzle velocities of 2049 and 2132 feet
94. From this it follows that with the E.G.F. 6-inch
Mark IV. gun and a projectile of 89 Ibs. nearly the same
velocity would be obtained from 28^ Ibs. of B.N. as from
48 Ibs. of E.X.E., and that with 3 tons per square inch less
maximum pressure. But this maximum would be about
39 inches nearer the muzzle.
95. Let it now be inquired how the new distribution of
pressure would affect the Mark IV. gun ?
It may be assumed that this gun has no superfluous
strength, especially in front of the trunnions ; indeed,
evidence is not wanting to show that the strength of existing
guns is deficient rather than excessive in this respect.
But let it be assumed that the present strength is suitable
for the pressures developed by a full charge of 48 Ibs. E.X.E.
96. Let the strength of the gun be examined at two points,
one at 64 inches, the other at 32 inches from the muzzle.
At the first point the gun consists of the A tube 1 75 inch
thick, and the B l tube 1 '385 inch thick.
32 SMOKELESS POWDER.
At the second point it consists of the A tube, 1 * 35 inch
thick, and the BX tube, 1'25 inch thick.
97. According to the principles laid down in the Official
Treatise on the Manufacture of Ordnance, 1886, no gun is
allowed to be strained beyond three-fourths of the elastic
limit of the material, which is fixed at 15 tons per square
inch for the A tube, and 18 tons for hoops or the
Consequently the allowed strain is 15 x = 11 '25 tons
for the A tube, and 18 x f = 13 '50 tons for the B tube.
98. Making use of the above dimensions, it will be found by
the usual formula that the greatest permissible pressure is
9 665 tons per square inch at 64 inches from muzzle, and
6 983 tons per square inch at 32 inches from muzzle.
99. Now, with the E.X.E. powder the pressures at these
points are about 10 tons and 8 tons^per square inch respec-
tively, so that the gun nearly answers to the required condi-
tions; but with the B.N. powder the pressures would be
14 tons and 10 tons per square inch respectively, an excess
of 4 tons in the first case and about 3 tons in the second.
100. It is therefore manifest that the strength of this gun
in the chase is quite insufficient for a charge of 28 f 52 Ibs. of
B.N. powder, and any less charge would give a less ballistic
101. It may be objected that the dotted curve Fig. 4 is
theoretical, and not based on actual observation, except as
regards the maximum pressure, and that the actual results
of firing have not shown the guns to be too weak.
102. With regard to the last objection, it has not much
weight. A gun may go on firing for a greater or less time
without bursting or any visible damage, but not the less
surely is it injured every time that it is strained beyond the
elastic limit, and this seems to be fully admitted at Woolwich,
where, as stated in the Official Treatise, the practice is to
limit the maximum strain to three-fourths of the elastic
limit. If, therefore, the present guns are not too strong for
the present powder, and if the pressure curves be even
SMOKELESS POWDER. 33
approximately correct, the guns cannot safely be used with
the new powder with increased ballistic effect.
103. The objection against the curve as theoretical carries
more weight. Not only is it theoretical, but it depends
on the assumption of the pressure in a close vessel being
78 * 52 tons per square inch.
The reason for this assumption is given above, and there is
nothing in it which appears either improbable or inconsistent
with such other facts as are known with respect to this
The law of decrease of pressure by which the ordinates and
the curves are calculated is a rational law, and in all pro-
bability approximately true for the powder gases.
104. Moreover, the velocities deduced from the area of
these curves (due allowance being made for other resist-
ances) agree very well with the observed velocities, and
consequently, whatever be the real form of the pressure
curve, its area must be approximately the same as that of the
dotted curve, Fig. 4.
105. In the next place, the final ordinate at the muzzle
must be the same (if all the charge is consumed), but it is
quite possible that the point of maximum pressure may be
further to the rear than shown in the curve, Fig. 4.
Indeed, the curve may possibly be of such a form as
shown in Fig. 5, A B C, the area of which may be the same
as that of A B t C. Even in this case the pressures in front
of the chase must be greater than with the other powder.
It may also be observed that, to permit of the possibility
of a curve of the form ABC, the rate of the evolution of
gas must be very different from anything previously known.
106. There is another strain besides the bursting strain
which must be provided for, viz. the longitudinal strain in
the chase of the gun arising from the friction of the products
of combustion rushing along the muzzle.
107. The importance of this strain has never been recog-
nised by gun-makers, nor do there appear to have been any
experiments made to ascertain its magnitude. In ' Internal
34 SMOKELESS POWDER.
Ballistics' reasons have been given for attributing to it a
very considerable magnitude, and indeed there can be little
doubt on the subject.
108. To what extent the magnitude of this strain will be
affected by the use of the new powder can only be conjec-
tured. On the one hand, the volume, pressure, and tem-
perature of products of combustion are considerably greater.
On the other hand, these products consist of nearly perfect
gases, and the coefficient of friction will probably be less
than in the mixture of gases and finely diffused liquid
arising from the combustion of the old powders.
109. The subject of the longitudinal strain is of such
importance that it is inconceivable to the author that gun-
makers have taken no steps to ascertain its magnitude and
relation to the other ballistic elements.
SMOKELESS POWDER. 35
INFLUENCE OF THE NEW POWDER ON THE DESIGN OF GUNS.
110. It has been shown that no great improvement in
ballistic effect can be looked for, consistent with safety,
with the present guns and the new powder. It is, there-
fore, proper to give some attention to the subject of a
design of gun suitable for the development of the new
111. Up to the present, the idea of gun-makers seems to
be running in the old groove low pressure and length of
The French 15 cm. Q.F. Canet gun is called a gun of
48 calibres, but that is the length over all. The real length
is as follows :
Chamber 50 inches -f chase 227-5 = 277 -5 inches.
It is only slightly chambered, and the equivalent length of
the chamber is 53 2 inches. The total capacity of the gun
is 7674 cubic inches, and of the chamber 1500 cubic inches,
so that it is a gun of 5 '116 expansions, that is to say, a very
112. But long guns are very inconvenient and objectionable,
especially at sea, and the question arises whether it would
be practicable to take advantage of the new powder in a
short gun, even though it were at the expense of decreasing
the efficiency per pound of powder.
113. The gun may be shortened in two ways : First, by
an enlarged powder chamber, which, however, has the dis-
36 SMOKELESS POWDER.
advantage of increasing the strain upon the breech apparatus ;
or, secondly, by increasing the maximum working pressure.
114. To what extent this may be done cannot at present
be solved in a general form, inasmuch as the relations be-
tween the ballistic effect of the new powder and the ballistic
elements, such as calibre of gun, travel and weight of pro-
jectile, and " characteristics " of the new powder are unknown
in this country.
115. Recourse must therefore be had to the method of
curves, and to such limited information as is given in the
published results contained in the first part of this paper.
The question will therefore be confined to a gun resembling
M. Canet's 15 cm. Q.F. gun with a calibre of 5*95 inches,
and travel and weight of projectile 224-5 inches and
116. Suppose (what might be easily done) a wire gun to
be made so as to give the same margin of safety under a
pressure of 30 tons as the Canet gun under a pressure of
By the formula (2), P = 0172 w 2 , and making P = 30, we
get w = 41 -76 Ibs., and consequently V = 198 wl = 3253 f.s.
Let the capacity of the chamber be 45 5 cubic inches per Ib.
of powder, which is the same gravimetric density as in the
last round of the Canet gun. (See Table II.)
The capacity of the chamber is 1500 cubic inches, and the
equivalent length 53 inches, and the length of charge
With these data the curve Fig. 6 is constructed, the area
of which is 301, which multiplied by the area of the pro-
jectile 27-4, gives 8247 foot-tons.
Deducting, as before, 20 per cent for resistances, expulsion
of gases, &c., there remains 6595 foot-tons, which corresponds
to a velocity of 3271 feet per inch, which is very nearly the
velocity found by the formula V = 198 wl.
117. The weight of this gun would probably be about
7J- tons, for on the wire construction it could be made con-
siderably lighter in proportion than the Canet gun.
SMOKELESS POWDER. 37
Therefore the relative efficiency of the two guns would be
Description of Gun.
Per Ton of
Per Ib. of
Showing the decided advantage of the high-pressure gun.
118. It may now be inquired, what would be the length of
the proposed high-pressure gun which would have the same
ballistic power as the Canet gun ?
This may be approximately ascertained from the curve
The difference of energy imparted to the projectile is
1933 foot- tons, to which must be added 20 per cent., making
c 47'- i
41. 76 Ws
2320 foot-tons, which divided by the area 27 * 4, gives 84 68
foot-tons to be deducted from the muzzle end of the curve,
and since the mean pressure near the muzzle is about
10 tons per square inch, the length to be deducted is
= 8*46 feet or 103 inches, so that the travel of the
projectile would be 122*5 inches and the total length of the
gun over all, about 181 inches instead of 283 inches in the
38. SMOKELESS POWDEE.
119. The two guns would have the same ballistic power.
The weights would be about the same, and the only difference
would be the expenditure of 41f Ibs. of powder instead of
120. With reference to the higher pressure proposed to be
used it is to be observed that the maximum pressure in a gun
depends not so much on the charge of powder as on Sarrau's
characteristic a, or rather on a 2 , which is in his notation
= - , in which/ is the " force " of the powder, a a coefficient
depending on the form of the grain, r the time of total com-
bustion of the grain in free air.
121. It is, therefore, obvious that with any given powder
for which / has a fixed value, the value of a 2 may be
modified by a corresponding modification of a and r, the first
of which depends on the form of grain, the second on its
density and least dimensions.
It is, therefore, simply an object of research to make a
powder of which the characteristics a, will give the required
122. As is easily seen, the higher pressure is given by the
lower value of r, whilst at the same time it may be effected
by giving such a form to the grain as will give a higher
value of a .
The practical result of decreasing r is that the evolution
of gas is quickened, and the pressure rises at an earlier
period of the course of the projectile, because the projec-
tile has not had time to move out of the way.
123. It is, therefore, evident that the question of the deter-
mination of the " characteristics " of these new powders, and
the size and form of grain suited to the different calibres
of guns, is one of first-rate importance, and without which
future ballistic progress must be a matter of hap-hazard
SMOKELESS POWDER. 39
124. Whilst the superiority of the new powder is incontes-
table, there is a danger that must be guarded against. The
very fact of its being a more powerful agent renders
precaution in its use the more necessary.
125. Its enormous " force " may be practically mitigated in
two ways first, by the size and density of the grain, which
governs the rate of evolution of gas, and secondly, by a
low gravimetric density such as has hitherto been used.
By a due adaptation of these, the rate of evolution of the
gas has been so proportioned to the space behind the pro-
jectile, that the pressures have been kept down to the
moderate limit which the new type guns can resist ; but if
by any cause, such as a change of constitution of the powder
under great variations of climate, or by breaking up of the
grains during transport, the rate of evolution of gas is sud-
denly increased, then the very high " potential " of the
powder may give rise to sudden abnormal increase of pressure,
which the guns may be quite unable to resist, and serious
accidents may occur.
126. These new powders are certainly more liable to
such changes of composition than the old powders, which
are simply mechanical mixtures, and therefore it is the
more necessary that the guns should be strengthened to the
utmost, rather than fined down to meet the requirements of
anticipated low pressures.
127. The general conclusions which may be drawn from
the preceding remarks are as follows :
(1) That the smokeless powder has ballistic properties far
superior to the old powders.
40 SMOKELESS POWDER.
(2) That the erosive action on the guns will probably be
(3) That its use in existing guns of the new forged steel
type will not lead to any considerable increase of ballistic
effect without considerable risk, owing to the increase of
pressure developed in the front part of the chase, although
the actual maximum pressure on the gun may be less.
(4) That to utilise the high ballistic powers of the new
powders very strong guns will be required, and that such
guns will have to be much stronger in front of the trunnions
than those of the new type forged steel guns.
That to arrive at very high ballistic results it is not
necessary to have guns of inordinate length, but by the
adoption of higher initial, instead of low and more uniform
pressures, velocities of 3000 feet per second and upwards are
attainable with perfect safety.
128. In bringing these remarks to a conclusion, the author
may perhaps be allowed to give expression to opinions, which
in his own mind amount to convictions, as to the future of
gun construction and ballistic effects.
129. The first of these is, that low maximum pressure is a
mistake. It has no raison d'etre except the weakness of the
gun. It involves a length of gun which for naval use k is
most objectionable. No doubt M. Canet has achieved very
brilliant results with his 15 cm. Q.F. gun, but this gun is
23 feet 4 inches in length over all. A " similar " gun
of 12 inch calibre would be about 46 feet 8 inches long.
" Similarly " loaded it would fire a charge of B.N. powder
of 264 Ibs., and a projectile of 712 Ibs., with a muzzle velocity
of 2750 . feet per second, giving a muzzle energy of 37,330
foot-tons, or 848 3 foot-tons per inch of circumference.
Now, as was shown in ( 118), a 15 cm. gun of equal power,
firing with a maximum pressure of 30 tons per square inch,
would be 15 feet long, and a " similar " gun of 12 inch calibre
would be 30 feet long, as against 46 feet 8 inches for the
low pressure gun. There can be no doubt which gun is the
most suitable for naval service.
SMOKELESS POWDER. 41
130. A second conviction is, that guns of a very large
calibre are a further mistake, and the author ventures to
think that a 9-inch or 10-inch high pressure gun would be
sufficient for any effect that is required against the heaviest
131. A third conviction is, that in order to utilise the new
powders recourse must be had to the wire system of con-
struction, by which alone guns of sufficient strength can be
132. Lastly, he would express the opinion that no time
should be lost in carrying out such a series of experiments
as will enable formulae analogous to those of M. Sarrau to
be constructed for these new powders, and also for the
determination of the tensile strain on the chase caused by
the friction of the products of combustion.
( 42 )
DECOMPOSITION OF NOBEI/S POWDER AS A TYPE OF THE
According to Nobel's specification, No. 1471/88, 100
grammes of powder contain
Perchloride ammonia 50*35
After explosion these give rise to new products, viz. :
From the Nitroglycerine.
Carbonic acid 13-435
Total .. .. 23-10
From the Nitrocellulose.
Carbonic acid 10-670
Carbonic oxide 6*791
Nitrogen .. 3*112
Total . 23-10
APPENDIX A. 43
From the Camphor.
Total .. .. 3-47
From the Perchloride of Ammonia.
Hydrogen .. .. 1-39
Total .. .. 50-35
Certain of the products of the camphor and perchloride
unite, and the final result of the decomposition is
Carbonic acid , 41-26
Total . 100-00
VOLUME OF GASEOUS PEODUCTS.
The volume of the products in the last paragraph at
Centigrade and * 76 metres of mercury would be
Carbonic acid 20-87
Watery vapour 31*31
Chlorine .. 8-21
Total . 70-51
44 APPENDIX A.
Therefore, from 1 gramme of powder the volume of gas
= *7051 cubic decimetres, or 705*1 cubic centimetres.
In the above the water has been considered as in the state
of a permanent vapour, though of course that is impossible at
Centigrade, but as forming part of the products of com-
bustion it is always in the gaseous form, and may therefore
properly be comprised among the gaseous products, proper
allowance being of course made when the evolution of heat
is considered, for the heat absorbed in the vaporisation of
HEAT EVOLVED PER GKAMME OF POWDER.
Keverting to the 100 grammes of powder, the heat evolved
is that evolved in the formation of 42 26 grammes of car-
bonic acid and 25 24 grammes of water. The first contains
11-25 grammes of carbon, and the second 2 '80 grammes of
Consequently the heat evolved is
From Carbon .. 11-25 x 8-08= 90 9 units Centigrade.
Hydrogen 2-80x34-46= 96-5
Total .. .. 187-4
but the heat required to vaporise 25 '4 grammes of water is
25-4 x '631 = 15-92 units Centigrade.
Deducting which there remains 171-48 units, or for
1 gramme of powder 1*7148 units Centigrade.
TEMPERATURE OF PRODUCTS.
This can only be given as a comparison with other
powders, and not as the real temperature existing in the
gun under circumstances when the loss of temperature due to
cooling and the specific heat at very high pressure and tem-
perature are both unknown.
APPENDIX A. 45
The temperature now in question is what might be called
the potential temperature or the theoretic temperature, and
is calculated on the assumption that there is no loss by
cooling, and that the specific heat remains constant.
Under these conditions it may be compared with the
potential or theoretic temperature of ordinary powders.
NOBEL'S POWDER. MEAN SPECIFIC HEAT OP PRODUCTS.
Carbonic acid .. .. 41-26 x '172 = 7-097
Nitrogen 13-86 x '173 = 2-398
Watery vapour .. .. 25-40 x '337 = 8-506
Chlorine 16-64 x '086 = 1-431
Oxygen 2-96 x '155 = 0-459
Therefore the mean specific heat = 199.
Since the heat evolved is 1*7148 units per gramme, or
1714 * 8 units per kilogramme, the temperature will be
-- = 8673 C.
( 46 )
In order to compare with the Nobel powder, Pebble powder
is taken as a type of the old powders, and its composition, as
given by Noble and Abel in their * Kesearches on Explosives '
(' Trans. Koyal Society/ 1880), is
Sulphate (sic) -0009
Hydrogen .. -0042
And the products of combustion of 1 gramme at Cent,
and * 76 metres of mercury
Grammes. Vols. in cm. 3
Carbonic acid -2627 .. 132-9
Carbonic oxide '0468 .. 37-1
Nitrogen.. .. '1099 .. 87-5
Sulphydric acid -0109 .. 9'2
Marsh gas .. '0006 .. 0-8
Hydrogen -0006 .; 6-7
Watery vapour '0006 .. 11-7
The remaining products consist of about 56 gramme of
salts, chiefly of potassium and sulphur, which whilst in the
gim are in the form of a liquid diffused throughout the gases
and at the same temperature.
APPENDIX B. 47
The heat evolved from 1 gramme of powder is that due to
the combustion of the carbon and hydrogen in it.
The carbon is as follows :
From Carbonic acid .. -2627 X A = '0717
Carbonic oxide .. -0468 X -& = '0201
Marsh gas .. .. -0006 x f = -0005
The hydrogen is
In Sulphydric acid .. .. -0109 x T V = '00063
Marsh gas -0006 X | = '00009
Water -0006 X i = -00006
-0095 X i = '00106
Consequently the heat evolved is
From Carbon to Carbonic acid .. -0717 x 8-08 =0-5793
Carbonic oxide .. -0201x2-473= -0497
Marsh gas .. .. -0005 x 8-08 = -0041
Hydrogen -00184 X34-46 = -0634
From this must be deducted the heat required to vaporise
the water, or
0101 x -631 = -0063
MEAN SPECIFIC HEAT.
This is given by Noble and Abel as 187.
TEMPERATURE (POTENTIAL OR THEORETIC).
The heat evolved from 1 kilogramme is 690 '2 units,
therefore temperature -7537" == 3690 Cent.
VELOCITY AND PRESSURE IN 5-905 INCH Q.F. CANET GUN WITH
54 LBS. P. POWDER.
Log o )8~
Log o a
FORMULA FOR VELOCITY. (' Internal Ballistics, p. 137.)
= m a p - 7
FOR PRESSURE :
P = Ka*A(^y
\ c 2 /
logK = -61174
>, * F* =
a 2 = -43223
,J W* =
A = -00000
w^ = -86619
.-. V = 2570 f. s.
logc 2 = 1-54249
.-. P = 22-00
WHILST the above pages were passing through the press
I have read an interesting article, in the* United Service
Magazine ' of August 1890, by Professor Lewes, of the Eoyal
Naval College, on "The Present State of the Powder
Question." Agreeing generally in the Professor's con-
clusions, I must take exception to one or two of his remarks.
I do not agree that a perfect powder is one of which the
production of gas goes on until the projectile reaches the
muzzle of the gun. Such a powder would be very wasteful,
and would carry the region of high pressure much too far
forward in the gun.
Then, again, I think there must be some mistake in the
diagram which is given as representing the pressures in the
chase with the three powders P 2 , Bl. Prism, and Br. Cocoa.
The areas of the three curves A, B, and C, if correct, must
be proportional to the muzzle energies of the projectile. The
velocities are proportional to the square roots of the re-
spective energies, that is to say, to the square root of the
areas of the curves.
Now, these three curves are represented by the relative
numbers 69 * 5, 76, and 67 5, the square roots of which are
8-33, 8 72, and 8 22, respectively.
Consequently, assuming the velocity of 1608 feet per
second to be correct for the P 2 powder, the other velocities
as represented by the curves would be, Black Prismatic
1683 feet, and Brown Cocoa 1586 feet per second, instead
of 1708 and 1798 feet per second as given by Professor
Lewes. It is therefore evident that there must be some
mistake in the curves shown in the diagram.
I am very glad to see that Professor Lewes insists strongly
on the importance of the question of the stability of the
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